This program project is intended to study tissue characterization by high field nuclear magnetic resonance in humans in the second half of the program. The 3.0T system for animal research will be used throughout the program for developing software and testing concepts and pulse sequences to be used in the other larger magnets. The program has a broad, multidisciplinary base including physicists, engineers, mathematicians, spectroscopists, computer scientists, radiation biologists, neurologists, neurosurgeons, neuropathologist and radiologists. It draws extensively on a vast array of resources at Columbia University College of Physicians and Surgeons and encompasses expertise and resources from the Bell Laboratories and the State University of New York at Stony Brook. The biological focus is brain tumors. The methodology, however, is applicable to other parts of the body. Sodium imaging and selective compartmental analysis of exta and intracellular spaces is investigated as a predictor to the grade of brain tumors. Proton chemical shift imaging and localized magnetic resonance spectroscopy will be developed with a novel set of pulsed gradients that allow a new approach to spatial localization, permit the expansion of the dynamic range of the system by more than 20 dB, improve the signal to noise ratio, reduce artifacts due to nonlinearity of the system and seem to increase spectral resolution. New mathematical algorithms will be investigated as an alternate to the Fourier Transform Method for the purpose of improving signal to noise and reducing truncation artifacts from strong signal peaks such as that of water in proton spectroscopy. A safety study is proposed before patients are investigated in the 5.0T magnet system. Such a high field strength is without precedent in clinical nuclear magnetic resonance, hence, the need for the safety study. The program includes the following projects: Project I - Grading of Brain Tumors MR Sodium Imaging Project II - Proton Chemical Shift Imaging Project III - Data Processing for chemical shift imaging Project IV - High Order Magnetic Field Gradients for MR Project V - Study of Safety in MR Imaging up to 5.0T